What is a Ballistic Compensation Calculator?
What is a Ballistic Compensation Calculator?
To answer that question, we have to first understand that in the real world, projectiles do not travel in a straight line and therefore one must compensate for environmental factors to ensure a projectile is able to accurately hit a target. Instead, projectiles both drop and curve based on the specific environmental factors and constraints that are present at the time a projectile is ejected (i.e. gravity, initial velocity, wind speed and direction, projectile shape and weight, altitude, temperature, etc.).
A ballistic compensation calculator provides information about the amount of compensation required to hit a target, at a specified distance away from the projectiles starting position, given the environmental factors that are present. Compensation values displayed in a ballistic compensation calculator are typically presented in the form of Minutes of Angle (MOA) or Milliradians (MIL) up or down and left or right.
What is Minute of Angle (MOA)?
Minutes of angle (MOA) is the typical unit of adjustment present on most rifle scopes. Some rifle scopes provide compensation values in Milliradians (MIL), but the same logic we will discuss here about MOA will also apply to MIL.
The word minute in minute of angle is just a fancy way of saying one sixtieth (1/60th) of something (i.e. the same way one minute is 1/60th of an hour). In this case we’re talking about 1/60th of an angle and the angle we're referring to one degree. So one minute of angle translates into 1/60th of a degree.
Minutes of Angle are used in long range compensation calculations because they translate nicely into distance measurements. More specifically 1 MOA of compensation translates into approximately 1 inch per 100 yards. Technically its 1.047 inches, but using round numbers will make our lives much easier for illustrative purposes.
So therefore, if you were to angle the barrel of a rifle upward at 1 MOA, your bullet would hit approximately one inch higher at 100 yards than it would if you were to not angle your barrel at all.
Because the bullet will keep traveling outward and upward after reaching 100 yards, the value of this upward compensation continues to grow at further and further distance. In other words, 1 MOA of compensation at 200 yards equates to 2 inches, then 3 inches at 300 yards and so on.
Imagine you have to laser pointers and you're aiming them at a wall that is 100 yards away. One laser pointer is held flat while the other is angled upwards at 1 MOA. The dots on the wall located 100 yards away will be 1 inch apart. Now imagine you aim the laser pointers, in the same configuration, at a wall that is 200 yards away. The dots will now be located 2 inches apart because the laser beam continues to travel upward and outward as the distance increases.
Let's now use a real world example to illustrate this. Imagine you’re trying to hit a target at 400 yards and your bullet is currently hitting 8 inches below the target. In other words, your bullet needs to “come up” 8 inches. To achieve this we will compensate by angling the barrel of the rifle upward so that our bullet can travel the correct arc to hit our target. Based on what we learned earlier we know that 1 MOA at 400 yards translates into 4 inches of come up (1 inch per 100 yards). Because we need to come up 8 inches we will need 2 MOA of compensation.
What is Milliradian (MIL / MRAD)?
MIL or MRAD, is similar to MOA and is also an angular measurement. Each full circle (360 degrees) is divided into 6283.185 MIL. In other words, if you compare that to the 21,600 MOA in a circle (remember 1 MOA = 1/60th of a degree), you end up with 1 MIL being equivalent to 3.4377 MOA.
At a distance of 100 yards, you end up adjusting by around 3.6 inches for each MIL. Most MIL or MRAD scopes let you adjust by 1/10th of a MIL which effectively comes out to 0.36 inches at 100 yards.
You may be thinking, why did they invent this very strange unit of measurement. Well, in the metric world things become much more clear. 1 MIL is very close to 1 cm (or 10 mm) at 100 meters. To be exact, it’s 0.9999 centimeters at 100 meters.
In terms of compensation, the same logic we discussed around MOA applies to MIL. Similar to MOA then, at 200 meters you’re looking at 2 cm adjustment per click when you have a riflescope that adjusts by 0.1 MRAD per click.
The good news, our custom turrets, turret labels and free ballistic calculator all support both MIL and MOA so you don't have to choose one or the other, you can use what you're already familiar with.
How do you Zero A Rifle Scope?
When you add a scope to your rifle, one of the first things you’ll do is “zero your rifle” or in other words, set your rifle up so that the line of sight out of your scope (i.e. the center of your crosshairs) is perfectly set up to hit a target at your desired zero range without any amount of compensation. The distance you selected will be considered your “zero range” and is most commonly 100 yards.
To zero a rifle scope you’d typically go to some form of shooting range, and using your scope, aim at a target located at your desired zero range. Then you’d fire a number of rounds at your target and look at your results. Typically you’d notice that your rounds are hitting low and therefore you will need to come up though some form of compensation. Using the logic we discussed above, you will use the turret located on your scope to “come up” the necessary amount of MOA to hit the target. Then you’d reset the turret so that it is sitting at 0 MOA. This means that with zero visible compensation on your turret, your rifle is set up to hit a target at your zero range dead on.
Note that when you adjust the turret on a scope you are actually angling the front of the scope towards or away from the barrel of your rifle and thereby increasing and decreasing the angle of your barrel. When you increase the amount of MOA of compensation on your scope you are angling the barrel upwards without affecting your line of sight.
Sometimes you will need to adjust the scope left or right, but the same MOA principles apply. From there you’ll be able to use the scope’s turret to adjust for targets that are located at further distances.
Understanding all of this, we can now talk about what a Ballistic Calculator is actually doing. It considers all of the factors that will cause your bullet to drop as it travels along its flight path (i.e. gravity, initial velocity and velocity over time, pressure, temperature, etc.) and then provides you with the exact amount of compensation required to hit your target dead on. Let's say you wanted to hit a target at 400 yards, the calculator might determine that given your environmental factors, your bullet will hit 20 inches low. It would then tell you that you’ll need to come up 5 MOA so that you can hit your target dead on.
How Our Compensation Calculator Works
You’ll start by entering your specific environmental factors and constraints as well as some information about your ammunition and firearm (e.g. initial velocity, zero range, etc.). We also collect information about your rifle scope so we can provide you with compensation results that are specific to the measurement units of which your scope makes use. For example, each click on your turret will have a value that translates into MOA or MIL (e.g. one click = ⅓ MOA).
Note that you can hover over the question mark icon on any field to learn more about how that field will impact your calculation.
Once you've completed the form click the <strong>calculate</strong> button to generate your ballistic compensation drop chart. The chart will provide you with the amount of compensation required to hit your target as well as the speed and energy of your projectile given a set of specified distances.
If you'd like to learn more about each of the specific environmental factors, check out our list of frequently asked questions.
What is a Ballistic Coefficient?
We get asked this question a lot. Fortunately the answer is pretty simple.
The ballistic coefficient or drag model of a given projectile refers to the aerodynamic nature of its shape and is a measure of the projectiles ability to overcome air resistance in flight. Our calculator allows you to choose from a wide range of ballistic coefficients (G1 through G8) to ensure you obtain the most accurate compensation results. Note that a ballistic coefficient of G1 (Flat Base Ammunition) or G7 (Boat Tail Ammunition) is ideal for traditional hunting and varmint bullets at close to moderate distance.
Ammunition and Scope Presets
Let us do some of the work for you by leveraging our ammunition and scope presets. Selecting from our presets will automatically fill-in certain data on your behalf (e.g. scope height, scope click unit, ballistic coefficient, ammunition weight, etc.).
Developed with in British Columbia.
In partnership with VRG Interactive Inc.